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