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