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