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