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