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