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