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)(16,17)(18,23)(19,20)(21,25)(22,26)(27,28) involution — undirected(1,2,4,3)(5,6)(7,10)(8,9)(11,12)(13,15)(14,20)(16,27)(18,19)(21,26)(23,24)(6,9)(10,11)(13,16,19,22,18,27,15,25)(14,21,24,28,23,26,20,17)(5,7,8,12)(6,10,9,11)(13,17,19,21,18,28,15,26)(14,22,24,27,23,25,20,16)(1,3,4,2)(14,23)(16,27)(20,24)(22,25)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.