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