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