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