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