No, she cannot
42-2-101(3), C.R.S. provides:
“No person shall drive any motor vehicle upon a highway in this state unless such person has in his or her immediate possession a current driver’s or minor driver’s license or an instruction permit issued by the department under this article.”
"(5) No person who has been issued a currently valid driver's or minor driver's license or an
instruction permit shall operate a motor vehicle upon a highway in this state without having such license or permit in such person's immediate possession."
The law requires you to carry your license. If your sister only has an instruction permit in her possession, she must operate under its rules until she is in possession of her permanent license.
Just in case people think "highway" means a high-speed roadway, the CRS defines highway:
"Highway" means the entire width between the boundary lines of every way publicly maintained when any part thereof is open to the use of the public for purposes of vehicular travel or the entire width of every way declared to be a public highway by any law of this state.