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