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