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