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