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