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