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