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