I would think the GOP of Colorado (assuming this is not overturned) could just put the names of the Republican electors on the ballot. If they won they could vote for Trump.
On the primary ballot (in WV, at least), the voter is asked to select any of several delegates to the convention. The delegates are identified by whom they support.
On the general election ballot (in WV, at least), the voter is asked to select a slate of electors. The electors are identified by whom they are pledged to support.
In WV, at least, we don't "vote for President". We vote for delegates or electors.
Your State may vary.