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