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