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