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)(11,16)(12,15)(13,14)(17,18,21,19)(20,23,24,22)(28,35)(31,38)(33,39)(36,40)(1,3)(2,6)(4,7)(5,8)(9,11)(10,12)(13,16)(14,15)(25,26,29,32)(27,30,34,37)(28,31,35,38)(33,36,39,40)(2,7)(3,8)(9,12,14,16)(10,15,13,11)(17,19,21,18)(20,23,24,22)(25,26)(27,30)(28,31)(29,32)(33,36)(34,37)(35,38)(39,40)(1,3)(2,4)(5,8)(6,7)(9,12)(10,11)(13,15)(14,16)(17,20,21,24)(18,22,19,23)(25,27,29,34)(26,30,32,37)(28,33,35,39)(31,36,38,40)(1,4)(2,3)(5,6)(7,8)(9,13,14,10)(11,16,15,12)(25,28,29,35)(26,31,32,38)(27,33,34,39)(30,36,37,40)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.