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