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