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