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