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