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