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