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