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