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