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)(11,17)(12,20)(13,15)(14,18)(16,22)(19,24)(21,23)(28,35)(30,37)(31,36)(33,39)(9,11,13,19)(10,14,15,23)(12,21,22,18)(16,24,20,17)(25,26,29,32)(27,30,34,37)(28,36,35,31)(33,40,39,38)(2,5)(3,8)(6,7)(25,27)(26,30)(28,33)(29,34)(31,38)(32,37)(35,39)(36,40) involution — undirected(10,15)(14,23)(16,20)(17,24)(25,28,29,35)(26,31,32,36)(27,33,34,39)(30,38,37,40)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.