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