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