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