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