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