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