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