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