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