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