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