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)(11,19)(12,16)(13,17)(14,18)(15,21)(20,24)(22,23)(26,30)(27,31)(32,36)(33,38)(34,35)(39,40) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11)(10,15)(12,20)(13,22)(14,21)(16,23)(17,24)(18,19)(25,26,29,30)(27,31,35,34)(28,36,37,32)(33,39,40,38)(3,7)(5,8)(9,12,14,13)(10,16,18,17)(11,20,21,22)(15,23,19,24)(25,27)(26,31)(28,33)(29,35)(30,34)(32,38)(36,39)(37,40)(2,6)(3,7)(9,13,14,12)(10,17,18,16)(11,20,21,22)(15,23,19,24)(25,28,29,37)(26,32,30,36)(27,33,35,40)(31,38,34,39)(3,7)(5,8)(10,18)(15,19)(16,17)(23,24)(25,26,29,30)(27,34,35,31)(28,36,37,32)(33,38,40,39)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.