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