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