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