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