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