Nothing in the section of the Colorado Constitution, Article V, Section 1, which you quoted says that redistricting may be taken away from the general assembly.  Let's read that first line: "The legislative power of the state shall be vested in the general assembly consisting of a senate and house of representatives, both elected by the people . . . ."  The right of initiative and the right of referendum are preserved, yes, but nowhere does that excerpt say that redistricting can be taken away from the general assembly.