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