Instead of using unsightly or hard-to-find patches, try applying crazy glue to seal the hole or the leaky valve.
Tire Patch Kits
If you happen to have a tire patch kit in the garage, this works very well for holes in air mattresses.
Rubber Cement – Duct Tape Combo
While this might not be a permanent solution, it should get you through at least a couple of nights in an emergency. Duct tape will usually not stick to a mattress on its own, but combined with rubber cement it will do a much better job. Simply apply the rubber cement to the mattress surface, then place the tape over it and press the tape on the hole.