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