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