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