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