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