correction: if hunting coyotes, you'd want to go with a red lens. green is good for small game, but predators like coyotes don't really pick up the red at all.

if you have a spotlight already but the lens isnt red, go to any wal-mart and you can get some Krylon metallic spray paint in red color for probably less than 4 bucks. it's heat resistant to extreme temperatures and just spray the INSIDE of your lens with a nice even red coat. good luck