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