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)(13,14)(15,18)(16,24)(17,19)(20,23)(21,26)(22,25)(27,28) involution — undirected(2,3)(6,10)(11,12)(14,19)(16,25)(18,20)(21,22)(24,28)(26,27) involution — undirected(1,2,4,3)(5,7,9,8)(6,11,10,12)(13,15)(14,20)(16,22)(17,23)(18,19)(21,25)(24,27)(26,28)(1,3,4,2)(5,7,9,8)(6,11,10,12)(13,16,17,26)(14,21,19,24)(15,22,23,28)(18,27,20,25)(5,8,9,7)(6,11,10,12)(14,19)(15,23)(21,24)(22,28)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.