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