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