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