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