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