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