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