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