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