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