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