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