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