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