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