I have 6 hens, and am not set up to let them free-range.
I feed good-quality layer pellets soaked in water overnight. I feed this in the morning. In the afternoon, they get sprouted wheat and what kitchen waste I generate (not much), dried stinging nettle and fresh dandelions and chickweed when they've regrown from the last time I clipped them.
But what really made the difference in yolk color was alfalfa. They weren't interested in alfalfa hay, nor in horse alfalfa pellets. Finally, I tried soaking the horse pellets with the layer pellets. They now clean it all up and I get nice orange yolks. The alfalfa pellets are nice because they come in at 17% protein, the same as the layer pellets, so I don't have to worry about rebalancing for protein. I measure it out, and I am feeding 1 cup of alfalfa to 3 cups layer pellets.