If the department code isn't listed, it would be a simple fix. Just add in a column with that information, and then they can still color code (via conditional formatting as Skip suggested) the items according to the value in the department code.
Really, if the document is important at all, and it sounds like it is, then it SHOULD be redone, so that it is done correctly, and not just left in it's current condition b/c "that's the way it's been done." That answer has been proven to fail. Basically if a better method is available, and the costs would not outweigh the benefits, then WHY NOT?!
If you go the VBA route, then if any changes are necessary, you'd be the one to maintain it, from what it sounds like. Whereas if you do it within the Workbook itself - since it does sound like a simple/easy fix - then practically anyone could make the necessary changes.
Anyway, that's just my thought on it.. I'd seriously consider going Skip's route on such a simple task as this one..
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"If to err is human, then I must be some kind of human!" -Me