Here is our rankings of Colorado's House delegation based upon how liberal or conservative they are.
Most Liberal to Most Conservative:
Dianna Degette CD 1 Liberal Score of 97.69 PVI D+21
Jared Polis CD 2 Liberal Score of 97.25 PVI D+11
Ed Perlmutter CD 7 Liberal Score of 94.93 PVI D+4
John Salazar CD 3 Liberal Score of 92.54 PVI R+5
Betsy Markey CD 4 Liberal Score of 87.50 PVI R+6
Mike Coffman CD 6 Liberal Score of 2.54 PVI R+8
Doug Lamborn CD 5 Liberal Score of 0.84 PVI R+14
Nothing surprising here, the Representatives' voting patters mirror the partisan voting patterns of their districts. For comparison the State of Colorado has a PVI of D+0.
Sources: Progressive Punch for Progressive scores from 2009-2010. PVI from Wikipedia.