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