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