I just checked my 2010 and it looks like it should be covered in plastic behind the passenger rear wheel. Here's a 2005 video. Same location, but a little more exposed from the looks of it.

https://www.youtube.com/watch?v=Zwr8ArykP1I

And here's the parts diagram:

VAPOR CANISTER & RELATED PARTS. Fits: Chevrolet | Nalley Buick GMC Brunswick