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