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