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