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