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