Welcome to the forum. There is no wiring diagram for the trailer, but there is a wiring diagram for how to wire the 7 pin connection. You can find it in your owner's manual, or if you don't have one, you can download it at this website:
http://www.keystonerv.com/customer-s.../owners-manual
There may have been some changes in the wiring colors in the +12 VDC and ground. On previous RV's the +12VDC was red and the ground was black. In the current owner's manual, the +12VDC is black and the ground is white. Otherwise, the functions are also listed so there isn't any real risk of making a wiring error if you pay attention to what you're wiring to which position.
Good Luck.