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