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