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)(12,20)(13,14)(15,18)(16,21)(19,22)(23,24)(26,31)(27,35)(33,34)(36,37)(1,3,5,8)(2,6,4,7)(11,18)(15,17)(19,24)(22,23)(26,31)(32,38)(33,34)(39,40)(10,14)(15,17)(16,20)(22,23)(25,26,30,31)(27,32,35,38)(28,33,29,34)(36,39,37,40)(1,4,5,2)(3,7,8,6)(9,11,13,18)(10,15,14,17)(12,19,21,24)(16,22,20,23)(25,27,30,35)(26,32,31,38)(28,36,29,37)(33,39,34,40)(9,10)(11,15)(12,16)(13,14)(17,18)(19,22)(20,21)(23,24)(25,28,30,29)(26,33,31,34)(27,36,35,37)(32,39,38,40)(9,12,13,21)(10,16,14,20)(11,19,18,24)(15,22,17,23)(25,29,30,28)(26,34,31,33)(27,37,35,36)(32,40,38,39)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.