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