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