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