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