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