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