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