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