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