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