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