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