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