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