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