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