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