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