To tune for your tastes you can experiment with the following console command. Numbers here are the initial values I found pleasing.

SCP 1.5 7 0.75
Where first value is saturation, second is brightness and third is contrast
Details found at http://www.uesp.net/wiki/Skyrim_talk:Console/Archive_1
This seems to set the saturation, brightness and contrast for the game period. You will likely want to restart after using it.

To tune the esp to your tastes open the esp in TES5Edit and set the parameters showin in the included image.