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