I'm not too keen on elves, and haven't touched that particular tileset yet. But I did get the ratmen working.
Tip: If you take a screenshot with PrintScreen, paste it into Paint(or your photo-editing tool of choice), and crop down to just the 176x80 magenta portion, that seems to clear whatever funky metadata was causing a rendering problem. I've got it working fine under PNG; I imagine it'd work similarly well converted to a 24-bit bitmap for 40d, but since I'm using 40d16, I haven't done so myself.
Here's a functional graphics file for it.
graphics_ratman
[OBJECT:GRAPHICS]
[TILE_PAGE:RATS]
[FILE:ratman/ratman.png]
[TILE_DIM:16:16]
[PAGE_DIM:11:5]
[CREATURE_GRAPHICS:RATMAN]
[DEFAULT:RATS:0:0:AS_IS]
[CHILD:RATS:1:0:AS_IS:DEFAULT]
[BABY:RATS:2:0:AS_IS:DEFAULT]
[DRUNK:RATS:3:0:AS_IS:DEFAULT]
[MERCHANT:RATS:4:0:AS_IS:DEFAULT]
[TRADER:RATS:4:0:AS_IS:DEFAULT]
[SHOPKEEPER:RATS:4:0:AS_IS:DEFAULT]
[ADMINISTRATOR:RATS:5:0:AS_IS:DEFAULT]
[CLERK:RATS:5:0:AS_IS:DEFAULT]
[ARCHITECT:RATS:5:0:AS_IS:DEFAULT]
[TAXCOLLECTOR:RATS:5:0:AS_IS:DEFAULT]
[ALCHEMIST:RATS:5:0:AS_IS:DEFAULT]
[DUNGEONMASTER:RATS:5:0:AS_IS:DEFAULT]
[MAYOR:RATS:5:0:AS_IS:DEFAULT]
[MANAGER:RATS:5:0:AS_IS:DEFAULT]
[BOOKKEEPER:RATS:5:0:AS_IS:DEFAULT]
[BROKER:RATS:5:0:AS_IS:DEFAULT]
[EXECUTIONER:RATS:6:0:AS_IS:DEFAULT]
[DIPLOMAT:RATS:7:0:AS_IS:DEFAULT]
[GUILDREP:RATS:7:0:AS_IS:DEFAULT]
[OUTPOSTLIAISON:RATS:7:0:AS_IS:DEFAULT]
[MERCHANTBARON:RATS:7:0:AS_IS:DEFAULT]
[MERCHANTPRINCE:RATS:7:0:AS_IS:DEFAULT]
[BARON:RATS:8:0:AS_IS:DEFAULT]
[BARON_CONSORT:RATS:8:0:AS_IS:DEFAULT]
[COUNT:RATS:8:0:AS_IS:DEFAULT]
[COUNT_CONSORT:RATS:8:0:AS_IS:DEFAULT]
[DUKE:RATS:8:0:AS_IS:DEFAULT]
[DUKE_CONSORT:RATS:8:0:AS_IS:DEFAULT]
[PHILOSOPHER:RATS:9:0:AS_IS:DEFAULT]
[ADVISOR:RATS:9:0:AS_IS:DEFAULT]
[KING:RATS:10:0:AS_IS:DEFAULT]
[KING_CONSORT:RATS:10:0:AS_IS:DEFAULT]
[LEADER:RATS:10:0:AS_IS:DEFAULT]
[MINER:RATS:0:1:AS_IS:DEFAULT]
[WOODWORKER:RATS:1:1:AS_IS:DEFAULT]
[CARPENTER:RATS:1:1:AS_IS:DEFAULT]
[BOWYER:RATS:1:1:AS_IS:DEFAULT]
[WOODCUTTER:RATS:1:1:AS_IS:DEFAULT]
[FARMER:RATS:2:1:AS_IS:DEFAULT]
[CHEESE_MAKER:RATS:2:1:AS_IS:DEFAULT]
[MILKER:RATS:2:1:AS_IS:DEFAULT]
[COOK:RATS:2:1:AS_IS:DEFAULT]
[THRESHER:RATS:2:1:AS_IS:DEFAULT]
[MILLER:RATS:2:1:AS_IS:DEFAULT]
[BUTCHER:RATS:2:1:AS_IS:DEFAULT]
[TANNER:RATS:2:1:AS_IS:DEFAULT]
[DYER:RATS:2:1:AS_IS:DEFAULT]
[PLANTER:RATS:2:1:AS_IS:DEFAULT]
[HERBALIST:RATS:2:1:AS_IS:DEFAULT]
[BREWER:RATS:2:1:AS_IS:DEFAULT]
[SOAP_MAKER:RATS:2:1:AS_IS:DEFAULT]
[POTASH_MAKER:RATS:2:1:AS_IS:DEFAULT]
[LYE_MAKER:RATS:2:1:AS_IS:DEFAULT]
[WOOD_BURNER:RATS:2:1:AS_IS:DEFAULT]
[STONEWORKER:RATS:3:1:AS_IS:DEFAULT]
[ENGRAVER:RATS:3:1:AS_IS:DEFAULT]
[MASON:RATS:3:1:AS_IS:DEFAULT]
[CRAFTSMAN:RATS:4:1:AS_IS:DEFAULT]
[WOODCRAFTER:RATS:4:1:AS_IS:DEFAULT]
[STONECRAFTER:RATS:4:1:AS_IS:DEFAULT]
[LEATHERWORKER:RATS:4:1:AS_IS:DEFAULT]
[BONE_CARVER:RATS:4:1:AS_IS:DEFAULT]
[WEAVER:RATS:4:1:AS_IS:DEFAULT]
[CLOTHIER:RATS:4:1:AS_IS:DEFAULT]
[GLASSMAKER:RATS:4:1:AS_IS:DEFAULT]
[STRAND_EXTRACTOR:RATS:4:1:AS_IS:DEFAULT]
[FISHERMAN:RATS:5:1:AS_IS:DEFAULT]
[FISHERY_WORKER:RATS:6:1:AS_IS:DEFAULT]
[FISH_DISSECTOR:RATS:6:1:AS_IS:DEFAULT]
[FISH_CLEANER:RATS:6:1:AS_IS:DEFAULT]
[ENGINEER:RATS:7:1:AS_IS:DEFAULT]
[MECHANIC:RATS:7:1:AS_IS:DEFAULT]
[SIEGE_ENGINEER:RATS:7:1:AS_IS:DEFAULT]
[SIEGE_OPERATOR:RATS:7:1:AS_IS:DEFAULT]
[PUMP_OPERATOR:RATS:7:1:AS_IS:DEFAULT]
[METALSMITH:RATS:8:1:AS_IS:DEFAULT]
[FURNACE_OPERATOR:RATS:8:1:AS_IS:DEFAULT]
[WEAPONSMITH:RATS:8:1:AS_IS:DEFAULT]
[ARMORER:RATS:8:1:AS_IS:DEFAULT]
[BLACKSMITH:RATS:8:1:AS_IS:DEFAULT]
[METALCRAFTER:RATS:8:1:AS_IS:DEFAULT]
[JEWELER:RATS:9:1:AS_IS:DEFAULT]
[GEM_CUTTER:RATS:9:1:AS_IS:DEFAULT]
[GEM_SETTER:RATS:9:1:AS_IS:DEFAULT]
[RANGER:RATS:10:1:AS_IS:DEFAULT]
[ANIMAL_CARETAKER:RATS:10:1:AS_IS:DEFAULT]
[ANIMAL_TRAINER:RATS:10:1:AS_IS:DEFAULT]
[HUNTER:RATS:10:1:AS_IS:DEFAULT]
[TRAPPER:RATS:10:1:AS_IS:DEFAULT]
[ANIMAL_DISSECTOR:RATS:10:1:AS_IS:DEFAULT]
[RECRUIT:RATS:0:2:AS_IS:DEFAULT]
[WRESTLER:RATS:1:2:AS_IS:DEFAULT]
[SWORDSMAN:RATS:2:2:AS_IS:DEFAULT]
[MACEMAN:RATS:3:2:AS_IS:DEFAULT]
[AXEMAN:RATS:4:2:AS_IS:DEFAULT]
[HAMMERMAN:RATS:5:2:AS_IS:DEFAULT]
[SPEARMAN:RATS:6:2:AS_IS:DEFAULT]
[BOWMAN:RATS:7:2:AS_IS:DEFAULT]
[CROSSBOWMAN:RATS:8:2:AS_IS:DEFAULT]
[CHAMPION:RATS:1:3:AS_IS:DEFAULT]
[CAPTAIN_OF_THE_GUARD:RATS:1:3:AS_IS:DEFAULT]
[SHERIFF:RATS:1:3:AS_IS:DEFAULT]
[MASTER_SWORDSMAN:RATS:2:3:AS_IS:DEFAULT]
[MASTER_MACEMAN:RATS:3:3:AS_IS:DEFAULT]
[MASTER_AXEMAN:RATS:4:3:AS_IS:DEFAULT]
[MASTER_HAMMERMAN:RATS:5:3:AS_IS:DEFAULT]
[MASTER_SPEARMAN:RATS:6:3:AS_IS:DEFAULT]
[MASTER_BOWMAN:RATS:7:3:AS_IS:DEFAULT]
[MASTER_CROSSBOWMAN:RATS:8:3:AS_IS:DEFAULT]
[PRIEST:RATS:0:4:AS_IS:DEFAULT]
[HIGH_PRIEST:RATS:0:4:AS_IS:DEFAULT]
[THIEF:RATS:1:4:AS_IS:DEFAULT]
[MASTER_THIEF:RATS:1:4:AS_IS:DEFAULT]
[SLAVE:RATS:2:4:AS_IS:DEFAULT]
[PRISONER:RATS:2:4:AS_IS:DEFAULT]
With that file saved as raw/graphics/graphics_ratman.txt and the tile page as raw/graphics/ratman/ratman.png and graphics turned on in data/init/init.txt, it should work. If you already have a graphics set installed, you'll want to go into its own .txt and remove any entry it has for [CREATURE_GRAPHICS:RATMAN](and until the next CREATURE_GRAPHICS token), but other than that it can install alongside existing graphics.
My playable ratman civ is as yet horribly unbalanced and not all that distinct from dwarves; I'm also playing with some other things as I go. But the .txt file includes every entry in the example .txt, so there shouldn't be any outright missing professions - only peasants should look like peasants(and, perhaps, regular ratmen on the map if playing without a ratman civ).
Anyway, so far so good, finally!
I haven't had major nobles arrive yet. One oddity so far, though: the expidition leader will show up with the "king/queen" graphics. This is not the case for the mayor; I don't know if the king is defined as the "site leader" or not. If not, then [LEADER:RATS:
10:0:AS_IS:DEFAULT] could be replaced by [LEADER:RATS:
5:0:AS_IS:DEFAULT] to use the standard "noble" graphic, or whatever else.
And here's the working .PNG file. Why this works when one with the same colours in the same place doesn't is beyond me, but anyway: