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