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