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