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