Yeah, I don't stop giving high quality foods to my mbuna cichlids; trying to improve their coloration.
About your breeding question, you always would like to have parent fishes with the best coloration, to pass this trait to their offspring. Then, if the parents don't have good coloration, there is a higher chance for their offspring to receive the dull color genes from their parents. Maybe there will be fry with good color, but the chances to be dull colored fry are higher if their parents are also dull colored.