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