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