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