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