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