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