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