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