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