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