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