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