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