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