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