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