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