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