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