I thought that there was a thread around here with a link to service manuals. Couldn't find it, but it doesn't mean that there isnt one... just have to search more. Anyway I haven't tried this one but I did download a service manual online (oem yamaha one) and in the last pages are the wiring diagrams. Here is a link to a manual you can download: http://maxmekker.com/atv/Manualer/yamaha/warrior.zip
Not sure if it works or not, but if it doesnt... just do a google search for a yamaha warrior service manual. Its out there.
You can also use the parts diagrams found on websites that sell oem parts (ie: dgy.com) if you are just looking for something simple.