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