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