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