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