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