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