One vertex per element, one color per generator, with an edge from x to x·s.
(5,8)(9,10,14,18)(11,16,20,24)(12,17,13,15)(19,22,21,23)(26,31)(27,34)(28,29)(33,37)(35,36)(38,39)(1,2)(3,5)(4,6)(7,8)(10,15)(12,13)(16,22)(17,18)(19,21)(23,24)(25,26)(27,32)(28,31)(29,37)(30,33)(34,38)(35,39)(36,40) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,11)(10,16)(12,21)(13,19)(14,20)(15,22)(17,23)(18,24)(25,27,30,36)(26,32,33,40)(28,34,29,35)(31,38,37,39)(9,12,14,13)(10,15,18,17)(11,19,20,21)(16,23,24,22)(25,28,30,29)(26,31,33,37)(27,35,36,34)(32,39,40,38)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.