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