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