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