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