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