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