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