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