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