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