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