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