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