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