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)(11,16,21,24)(12,13,17,14)(19,22,23,20)(25,26,30,35)(27,33,38,32)(28,39,37,40)(29,36,31,34)(1,3,5,4)(2,6,8,7)(9,11)(10,16)(12,19)(13,22)(14,20)(15,21)(17,23)(18,24)(25,27,30,38)(26,32,35,33)(28,31,37,29)(34,39,36,40)(1,3,5,4)(2,7,8,6)(9,12,14,10,15,17,13,18)(11,19,20,16,21,23,22,24)(25,28,31,38,30,37,29,27)(26,33,36,40,35,32,34,39)(1,4,5,3)(2,7,8,6)(9,13,15,14)(10,17,18,12)(11,20,21,22)(16,19,24,23)(25,29,30,31)(26,34,35,36)(27,37,38,28)(32,40,33,39)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.