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