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