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