How do you turn the safety off of a Diablo Mongoose 2 LCD paintball gun?

Check the left side of the trigger frame, if there is no safety switch there then it is a newer version and it has an electronic safety. Read your manual to find out how to disengage it.

If you don't have the manual go here:

http://www.pbnation.com/forumdisplay.php?f=332

They'll be more than happy to help.