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