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