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