The Pneumatic Bumper is the electronic part that plugs into the cRio control system. He's asking about wiring....which I have not explored. In the past it was typical to use #18 wire to connect them, but it would be wise to read thru the pneumatics manual, the control system manual, the Robot rules, and the FRC Suggestions.
http://usfirst.org/community/frc/content.aspx?id=452
I haven't looked, because we're not using pneumatics this year....