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