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