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