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