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