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