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