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