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