Hi! I just got back from Punta Cana ))) A week before that I had colored my hair. Even though we have spent almost 10 days under the sun and I was not wearing a hat - my hair color is still vibrant. I think there is nothing better than Sun Protection line from Goldwell. My favorite product is Goldwell Dualsenses Sun Reflects Leave In Protect Spray. It protects your hair form sun rays, plus detangles, moisturizes, non-greasy at all, and smells wonderful.
Another wonderful and award-winning product is Pureology Essential Repair Colour Max Sun protecting spray. Its 100% Vegan by the way. I use it a lot. I would have taken it on a trip with me, but the bottle was pretty big. This product is also a great hair repairing solution + detangler.
Hope that helps.