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