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)(13,14,17,19)(15,16,20,18)(22,26)(24,27)(6,8)(10,12)(13,15)(14,18)(16,19)(17,20) involution — undirected(1,2,4,3)(7,11)(10,12)(14,19)(15,20)(21,22)(23,27)(24,28)(25,26)(1,2,4,3)(5,7)(6,10)(8,12)(9,11)(13,15)(14,16)(17,20)(18,19)(21,23,25,28)(22,27,26,24)(1,3,4,2)(5,8,9,6)(7,12,11,10)(13,16)(14,15)(17,18)(19,20)(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.