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