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