Take US 70 west from Denver (or east from Grand Junction) to the Grizzly Creek rest stop (about 2-3 miles east of exit 116). Park and walk down to the river.
Finding the ideal spot to capture the scene may take a bit of time.
US 70 between Denver and Grand Junction is one of the most scenic and beautiful routes in the US. The stop at the Grizzly Creek presents a wonderful view of the canyon with steep cliffs on either bank (including a rail line on the south bank) and with plentiful vegetation lining each shore.