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