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