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