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