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