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