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