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