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