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