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