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