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