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