One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10)(11,13)(12,14)(15,16)(17,18)(19,28)(20,26)(21,25)(22,27)(23,30)(24,29)(31,32) involution — undirected(2,5)(6,8)(9,11)(10,13)(12,15)(14,16)(17,19,22,31)(18,23,27,24)(20,29,21,30)(25,32,26,28)(11,15)(13,16)(17,19)(18,24)(20,29)(21,30)(22,31)(23,27)(25,28)(26,32) involution — undirected(10,14)(13,16)(17,20,22,21)(18,25,27,26)(19,29,31,30)(23,32,24,28)(1,3,4,7)(2,6,5,8)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.