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