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