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