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