Fossils can tell us a lot about dinosaurs, but it's a heck of a job to rearrange all the bones to create a structure of a once-living animal. On the other hand, while we can get an idea of how big a dinosaur was, as well as some of its bodily features, there are other features that are nothing more than guesswork.
While you're probably used to thinking about Jurassic Park when you think about dinosaurs, there's a very good chance that dinosaurs looked nothing like what you've seen in movies. In fact, the movie dinosaurs are nothing more than fiction based off of early sketches of what dinosaurs "may" have looked like.
In reality, we have no idea what color dinosaurs truly were. We continue to scan fossils for potential clues into skin pigmentation, but so far, we haven't had much luck and all findings so far have been highly debatable.
We've been able to deduce from numerous fossil discoveries that dinosaurs were likely feathered rather than scaled, and we've even been able to determine the color of feathers, but determining the skin color has been a completely different challenge in and of itself.
Since fossils are preserved in gray rock-like states, it's hard to deduce color from them. Nevertheless, research continues until we find a way to tell an accurate story about early life on Earth.