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