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