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