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