I'm color blind and have been told by an ophthalmologist that my color vision is much like a deer's. I can see blues and yellows fine, but if they have greens and reds mixed in with them, I don't really see the difference, unless the added colors make it lighter or darker. Golf balls that other people call green look yellow to me; a purple shirt looks blue to me. Reds and greens and browns tend to look the same, unless it is a very vivid red, and then it looks red. Red roses look the same color to me as the surrounding leaves, unless the roses are lighter or darker shades than the leaves. Many times I have looked at a bush with red flowers on it and not noticed the flowers until I see the different shapes of the flowers from the leaves.
Based on my own color vision, I would say that arrows fletched in a drab red would be the least noticeable to a deer. Blue fletches would be less noticeable than white, for the reasons mentioned, but more noticeable than red. Orange fletches would be more noticeable than red, because the yellow content in orange makes them stand out to a person with my type of color blindness.
Green or brown fletches would work fine too, of course, but would be hard to find, whereas red, even a drab red, would be relatively easy to find for a person with normal color vision.