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)(14,17)(18,20)(21,22)(23,27)(24,26)(25,28)(6,9)(10,11)(21,22)(23,25)(24,26)(27,28) involution — undirected(7,12)(10,11)(13,14,16,17)(15,18,19,20)(21,22,24,26)(23,25,28,27)(1,2)(3,4)(5,7,8,12)(6,10,9,11)(13,14)(15,18)(16,17)(19,20)(21,22)(23,25)(24,26)(27,28)(5,6)(7,10)(8,9)(11,12)(13,15,16,19)(14,18,17,20)(21,23)(22,25)(24,28)(26,27)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.