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