I am not a nutrition guru, but have nearly 20 journeys around the SUN of chicken keeping experience. I can almost guess that you are feeding your hens Layer feed. (nothing wrong there) .. They probably do not get much free range feeding, or scratch/bird seed/ treats.. (just my thinking) . Your eggs will look just like all the rest of the CORPORATE EGGS from the grocery store. There are feeds that do include marigold in the mix. They are supposed to produce darker yolks. The brand is Nutrea natural, or something like that.. I can find the exact name, if you would like. It may take a little searching on my part.
This is what I do.
I feed my hens Allflock. pellets. I supplement their calcium needs with cracked oyster shells free choice. I give them a quantity of scratch,/ bird seeds / corn. I also give them all leftover kitchen scraps. ( nothing bad like sweets, salty, just mostly veggies and fruit). They free range.
The eggs have really nice dark yolks.
WISHING YOU BEST