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