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