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