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