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