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