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