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