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