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