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