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