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