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