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