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