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