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