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