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