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)(12,15)(13,16)(17,21)(18,22)(19,23)(20,24)(25,26,31,35,32,36,30,34)(27,37,28,40,39,29,38,33)(2,5)(6,8)(9,11)(10,14)(12,19)(13,17)(15,23)(16,21)(18,20)(22,24)(25,27,32,39)(26,33,36,40)(28,31,38,30)(29,34,37,35)(11,17)(14,21)(18,19)(22,23)(25,28)(26,29)(27,31)(30,39)(32,38)(33,34)(35,40)(36,37) involution — undirected(9,12,13,20)(10,15,16,24)(11,18,17,19)(14,22,21,23)(25,29)(26,28)(27,34)(30,40)(31,33)(32,37)(35,39)(36,38)(1,3,4,7)(2,6,5,8)(10,16)(14,21)(15,24)(22,23)(25,30,32,31)(26,34,36,35)(27,28,39,38)(29,33,37,40)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.