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