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