Duolingo is wrong here. The answer I put was "Tương lai của tôi là màu sắm," which I got wrong. "Tương lai của tôi có màu sắm" is what Duolingo told me was the correct answer, but that actually means "My future has gray."
If the translation was 'my gray future', would it be Tương lai màu xám của tôi? Just just trying to solidify the word order here. The prepositional/possessive phrase would come at the end to change the meaning, right?