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