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