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