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