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