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