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