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