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