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