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