its in the utility section
u hit the utility button and then hit SF2(keyboard) then you see the transpose button
look at the picture attached to this post.
u wanna look for the utility button, but it depends on what motif u have, 61,76, or 88 key
p.s. dont rely on the tranpose button learn your music in all keys so that if you go to a gig that has a keyboard you are not used to, you dont have to worry because u can play in all keys. just my two cents