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