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