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