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