I'm a bit OCD about getting "the right dwarf to the right job" (or at least making sure the entirely wrong dwarf doesn't get it, with reference to their attributes). I tend to go down the list orderly, in and out of checking attributes to see if anything's outstanding, and then go by (extremely short-term) memory about what job-sets I've already set, and whether or not the dwarf concerned has their full initial complement of assignment points still.
The colouring would add something, I suppose. Although if (frexample) I'd planned a farmer and a brewer (as separate people) it wouldn't give any more of a necessary hint than without, as to which of the two I had not yet assigned. Perhaps actually go the whole hog and make "Urist McUrist, Brewer", dynamically changing as appropriate to the current job (with similar precedence rules for drawn 'first-place' options, as mentioned).
 Does that show for you? Couldn't find the right word-colour for agricultural half-yellow, so used the 12-bit/3h notation. Might not work on all browsers, even if this does.