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