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