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