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