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