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