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