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