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