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