I think colours would be a great idea to have.
Not only for the bots, but also for the humans watching.
I've been fiddling around with an 6-sexed organism, which I have divided into 6 different bots, just to make it possible to seperate them.
This in turn leads to all kinds of trouble with one bot out-breeding the others.
I could make a single bot with an sex indicator, but this would make it difficult to see what each sex is actualy doing since they would all have the same colour.