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)(11,15)(12,18)(13,21)(14,16)(17,22)(19,20)(23,24)(25,26)(27,36)(28,29)(30,32)(31,33)(34,35)(37,40)(38,39)(3,7)(5,8)(9,11)(10,15)(12,16)(13,19)(14,18)(17,23)(20,21)(22,24)(25,27,31,30)(26,32,33,36)(28,39,35,37)(29,40,34,38)(1,2)(3,5)(4,6)(7,8)(10,16)(11,18)(17,21)(19,24)(26,33)(28,35)(32,36)(37,39) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,10)(11,12)(13,17)(14,16)(15,18)(19,20)(21,22)(23,24)(25,28,31,35)(26,34,33,29)(27,37,30,39)(32,40,36,38)(1,2)(3,5)(4,6)(7,8)(9,12)(10,11)(13,20)(14,15)(16,18)(17,19)(21,24)(22,23)(25,29,31,34)(26,35,33,28)(27,38,30,40)(32,39,36,37)(9,13,14,22)(10,17,16,21)(11,19,18,24)(12,20,15,23)(25,30,31,27)(26,36,33,32)(28,39,35,37)(29,40,34,38)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.