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