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)(11,22)(12,27)(13,20)(14,19)(15,21)(16,24)(17,25)(18,30)(23,32)(26,33)(28,38)(29,37)(31,36)(34,40)(35,39)(1,3,4,8)(2,5,6,7)(9,11)(10,16)(12,28)(13,25)(14,24)(15,26)(17,21)(18,35)(19,33)(20,22)(23,29)(27,34)(30,40)(31,39)(32,36)(37,38)(9,11)(10,17,21,16)(12,23)(13,24)(14,25)(15,26)(18,34,37,32)(19,33,20,22)(27,35,36,38)(28,29)(30,39)(31,40)(3,8)(5,7)(9,12,15,31)(10,18,21,37)(11,23,26,40)(13,30,14,29)(16,32,17,34)(19,27,20,36)(22,38,33,35)(24,39,25,28)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.