And if you want the actual colors to be equal to hair colors you would change the color parameter:
color = {field = :Eye, type = "nominal",
scale = {domain = ["Green", "Blue", "Hazel", "Brown"], range = ["#F1C40F", "#95A5A6", "#F1C40F", "#F1C40F"] } }
Changing the hex values to the proper colors.
However, it seems that the order of bars in the graph and legend entries is not the same. I wonder how one can fix this? More precisely, the vertical order of bars in the graph is alphabetical where as legend entries are in the order specified in “domain”.