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)(13,14,18,22,17,21,26,28)(15,19,24,20,23,27,16,25)(1,3,4,2)(5,7,9,8)(6,10,11,12)(13,15,17,23)(14,19,21,27)(16,18,24,26)(20,28,25,22)(5,8,9,7)(6,10,11,12)(13,16,26,23,17,24,18,15)(14,20,28,19,21,25,22,27)(2,3)(6,11)(10,12)(14,21)(19,27)(20,25)(22,28) 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.