One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10)(11,19)(12,18)(13,17)(14,16)(15,21)(20,24)(22,23) involution — undirected(2,5)(6,7)(9,11)(10,15)(12,20)(13,21)(14,22)(16,24)(17,19)(18,23)(25,26,29,32)(27,33,35,40)(28,36,38,31)(30,37,39,34)(10,16)(12,14)(15,23)(17,18)(19,24)(20,22)(25,27,29,35)(26,30,32,39)(28,37,38,34)(31,40,36,33)(1,3,4,8)(2,6,5,7)(9,12,13,14)(10,16,17,18)(11,20,21,22)(15,24,19,23)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.