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