Yes; most of it.

Quote Originally Posted by blm.gov
Unless specifically prohibited, public lands managed by the BLM are open to hunting. Always check with your local BLM office in the region you plan to visit to inquire about closures, restrictions and safety tips before you plan your trip.

and

Quote Originally Posted by blm.gov
The majority of the 8.3 million acres of BLM lands in Colorado are open to hunting under Colorado Parks and Wildlife regulations, including some of the best big game opportunities in the state. Later seasons are particularly popular as elk and mule deer move to lower elevations.

This link is for a BLM downloadable .pdf specifically regarding "Colorado Recreation" from the blm.gov site. (Note: Clicking the link begins the download)