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