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