You can get free USFS MVUM's (motor vehicle use maps) from the various US Forest Service ranger stations and online. The online maps are difficult to read IMO, and the paper maps are hard to use as well as they don't include any landmarks, only road numbers.
These maps are the only official route maps for the forests, and show a lot of open routes not in those trail books. If you like to go exploring, the MVUM's are for you. If you just want to go where everybody else does, TrailDamage is one of the best resources.
Here is were to see the MVUM's online... US Forest Service Motor Vehicle Use Maps
Scroll down the page to Colorado, or any other state for that matter for your official map of open routes in the forests