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