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