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