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