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