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