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