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