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