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