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