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