I'm not terribly up on your playing, but having hosted countless workshops at work, I maybe have a couple of pointers...
a) Don't just wail out in some wanky shit. People get bored. Doubt you will, but just so you know :yesway:
b) Guitarists fucking love gear chat. Don't be afraid to geek it out. Talk about what you have and why, what you used to use and why you moved away from it.
c) Shit jokes go down well, on rock poses and stuff.
d) What was said above about sevens is definitely a good shout. It's not necessarily an oddity amongst shredders, but it still is an unknown instrument to most. As seven string musicians it's ridiculous we're still shrugging off the Korn "just for drop tuned chugging" tag. Show what it does and why it is so much more than an instrument for playing Blind or Freak on a Leash.
e) Techniques that you favour that a little off the beaten path. We had a Taylor guy that did a whole bunch of tapping on acoustic. That went down well. We had a shredder guy come demo VHT stuff that did a whole bunch of flamenco shit. People loved it. When I demoed stuff in the shop I used to a bit of slide on my seven. Less known techniques, particularly in an out-of-genre setting always go down well.
f) Have fun. People are there because they want to know about how you tick. Fans. Amazing. You'll be fine dude!
g) Oh, one last thing (goes without saying!) be nice to your hosts! Never know what might happen. Again, you don't play the obnoxious rock god arsehole, but just stating the obvious!