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