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