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)(14,17)(15,32)(16,23)(18,27)(19,26)(20,30)(22,35)(24,37)(28,38)(31,33)(34,40)(36,39)(5,6)(7,8)(9,11,22,39,15,12,13,23,14,24,26,27,30,28,31,40)(10,16,33,25,20,36,19,21,17,34,29,38,32,18,35,37)(2,4)(6,8)(10,17)(16,34)(18,36)(19,35)(20,32)(21,37)(25,38)(29,33) involution — undirected(9,12,26,40,15,24,31,39,14,28,22,23,30,11,13,27)(10,18,29,21,20,16,35,38,17,36,33,37,32,34,19,25)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.