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