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