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