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