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