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