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