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