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