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