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