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