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)(15,25)(16,27)(17,24)(18,22)(19,23)(20,26)(21,28) involution — undirected(5,7)(6,9)(8,12)(10,11)(13,15,19,26)(14,20,23,25)(16,28,22,17)(18,21,27,24)(1,2,3,4)(13,16,17,15,19,22,28,26)(14,18,24,20,23,27,21,25)(6,10)(9,11)(13,17,19,28)(14,21,23,24)(15,16,26,22)(18,20,27,25)(7,12)(9,11)(13,18,17,20,19,27,28,25)(14,22,24,26,23,16,21,15)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.