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)(13,14,18,19)(15,23,26,20)(16,21,27,25)(17,22,24,28)(6,10)(11,12)(13,15)(14,20)(16,24)(17,27)(18,26)(19,23)(21,22)(25,28) involution — undirected(1,2,3,4)(5,7,9,8)(6,11,10,12)(14,19)(15,23)(16,25)(20,26)(21,27)(22,28)(5,8,9,7)(6,12,10,11)(13,16)(14,21)(15,24)(17,26)(18,27)(19,25)(20,22)(23,28)(13,17,18,24)(14,22,19,28)(15,25,26,21)(16,20,27,23)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.