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