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