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