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