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)(17,18,21,20)(19,22,23,24)(25,26,30,31)(27,32,33,28)(29,34,39,40)(35,38,37,36)(1,3,5,8)(2,6,7,4)(19,23)(22,24)(26,31)(28,32)(34,40)(36,38)(2,7)(3,8)(9,11,13,12)(10,14,16,15)(17,19)(18,22)(20,24)(21,23)(25,27,30,33)(26,32,31,28)(29,37,39,35)(34,36,40,38)(1,4)(2,3)(5,6)(7,8)(9,10)(11,14)(12,15)(13,16)(17,18,21,20)(19,22,23,24)(25,28,30,32)(26,33,31,27)(29,38,39,36)(34,35,40,37)(1,2)(3,6)(4,8)(5,7)(9,12,13,11)(10,15,16,14)(17,20,21,18)(19,24,23,22)(25,29,30,39)(26,34,31,40)(27,35,33,37)(28,36,32,38)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.