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