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