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