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