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