You can adjust the camber by releasing shock absorber bolts (marked in the picture).

Untighten, adjust, tighten back.

Negative camber will also increase as the suspension compresses. So if the bike is carrying a heavy load with the softer springs and without increased preload, the wheels will camber in quite a bit.

How to increase or decrease the preload.

If those won't help it may be that the shock is worn (or bent) and needs replacement.