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