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