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