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