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