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