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