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