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