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)(25,26,30,28)(27,34,35,40)(29,33,31,39)(32,37,36,38)(1,3,5,4)(2,6,7,8)(9,11)(10,14)(12,18)(13,17)(15,21)(16,20)(19,23)(22,24)(26,28)(27,35)(33,39)(37,38)(11,17)(14,20)(18,23)(21,24)(25,27,29,37,30,35,31,38)(26,32,39,40,28,36,33,34)(1,4,5,3)(2,6,7,8)(9,12)(10,15)(11,18)(13,19)(14,21)(16,22)(17,23)(20,24)(25,28,30,26)(27,36,35,32)(29,33,31,39)(34,38,40,37)(12,19)(15,22)(18,23)(21,24)(25,29,30,31)(26,33,28,39)(27,37,35,38)(32,34,36,40)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.