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