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)(13,14)(15,20)(16,27)(17,24)(18,23)(19,25)(21,26)(22,28) involution — undirected(1,2,3,4)(5,7)(6,9)(8,12)(10,11)(13,15)(14,20)(16,18)(17,28)(19,26)(21,25)(22,24)(23,27)(7,12)(9,10)(13,16,19,28)(14,21,25,20)(15,17,26,18)(22,23,27,24)(5,7)(6,10)(8,12)(9,11)(13,16)(14,22)(15,17)(18,26)(19,28)(20,23)(21,24)(25,27) involution — undirected(7,12)(9,10)(13,17,19,18)(14,23,25,24)(15,16,26,28)(20,22,21,27)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.