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