Hello and thank you for reaching out to Petco Pet Education Center, formerly Petcoach. It is thought that dogs mostly see very muted colors, with green being the best color they see, and red/orange the worst. This may explain why lots of dogs prefer tennis balls, since they are such a bright green color. Most dogs will not have any preference in the color of their toys, but it's possible that The Coach will like a bright green toy the best. I hope this is helpful! Best of luck with The Coach!