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