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