One vertex per element, one color per generator, with an edge from x to x·s.
(1,2) involution — undirected(3,4)(5,6)(7,8,13,18)(9,19,22,32)(10,15,23,29)(11,17,12,16)(14,26,28,21)(20,33,34,38)(24,31,25,30)(27,36,37,35)(7,9)(8,14)(10,20)(11,21)(12,26)(13,22)(15,27)(16,19)(17,32)(18,28)(23,34)(24,35)(25,36)(29,37)(30,33)(31,38) involution — undirected(4,6)(7,10)(8,15)(9,20)(11,24)(12,25)(13,23)(14,27)(16,30)(17,31)(18,29)(19,33)(21,35)(22,34)(26,36)(28,37)(32,38) involution — undirected(10,23)(15,29)(20,34)(24,25)(27,37)(30,31)(33,38)(35,36) involution — undirected(7,11,13,12)(8,16,18,17)(9,21,22,26)(10,24,23,25)(14,19,28,32)(15,30,29,31)(20,35,34,36)(27,33,37,38)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.