Dinosaur National Monument is in northeast, Utah. I believe (I am writing this 18 months after the trip) I drove west on 40 to Colorado to 64 to 139 south to Interstate 70 to 141. It was a great drive. The photos don't really do it justice. Quite enjoyable and scenic.
Photos from a 2 week vist to Utah, Colorado and Arizona in September to October. During the trip I visited Salt Lake City, Utah; Antelope Island, Great Salt Lake; Mount Timpanogos; Dinosaur National Monument and Mesa Verde.