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