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