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