Pellet feed for chickens kept in an enclosed space normally has colourants added to it. Some are just a dye labelled as 'yolk enhancer' and some are a natural colourant like dried and powdered marigold petals. Naturally chickens eat a lot of grass and other leaves which colours the yolks and we have fed then finely chopped dark green cabbage to get the same effect, because our feed at the time had no colourants at all. We did experiment once with no colourant and the result was yolks so pale they weren't much different to the yolk.
As to the taste, there is a genetic condition which imparts a 'fishy' taste to the egg. Whilst the are edible they don't taste that nice and based on one hen we have now (Verity) they don't improve very much in time, although I can now eat them, whereas before we were throwing them away. In all the hens we have had (perhaps 100) this is the only one with the condition, so I'd try a better quality feed first- another brand more expensive, because in my experience cheap feed is exactly that, cheap quality. Avoid anything containing a cheap fish by-product based protein, which you can usually smell in the food anyway.