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