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