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