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