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