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