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