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