As they get into the middle of the laying season, they will get some fading, but usually in the early stage of it, they should be yellow. Legs will be a richer yellow if they are free ranging or out getting some kind of natural diet they find on their own too as it gives them a more varied diet. You could try to figure out who is laying which eggs and track them too. It takes a lot of work if you don't know who's egg is who's and you have some that are too similar in shape and color.