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