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