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