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