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