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