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