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