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