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