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