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