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