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