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