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