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